Carbon Offsets for Urban Trees Are on the Horizon

By Maria Dolan
Austin, Texas, and King County, Washington, are testing carbon credits for planting and protecting urban trees.

The evidence is in: Urban trees improve air and water quality, reduce energy costs, and improve human health, even as they offer the benefit of storing carbon. And in cities across the country, they are disappearing.

A recent paper by two U.S. Forest Service scientists reported that metropolitan areas in the U.S. are losing about 36 million trees each year. The paper, by David Nowak and Eric Greenfield, was an expansion of the same researchers’ 2012 study that found significant tree loss in 17 out of the 20 U.S. cities studied.

This arboreal decline is happening even in some areas that promote “million-tree” campaigns, Arbor Day plantings, and street-tree giveaways. Cash-strapped municipalities just can’t find enough green to maintain the green. Additionally, many cities are adjusting to population booms, and to temperature increases and drought due to climate change—both conditions that can be hard on trees (while increasing their value as sources of cooling and cleaner air). There’s also a growing recognition of the inequity of tree-canopy distribution in many cities, with lush cover in wealthy neighborhoods and far fewer trees in disadvantaged areas.

To find more funding for urban trees, some local governments, including Austin, Texas and King County, Washington (where Seattle is located), are running pilot projects with a Seattle-based nonprofit called City Forest Credits (CFC). The nonprofit is developing a new approach: generating funding for city tree canopies from private companies (and individuals) that wish to offset their carbon emissions by buying credits for tree planting or preservation.

The vast majority of forest carbon credits worldwide have been issued for trees in tropical rainforests and other forests far from urban areas. A study released last year of the forest offsets in California’s cap-and-trade program found that they are effective at reducing emissions.